The present invention relates to an improvement of an electrical connecting box to be installed on a vehicle, in which water is naturally discharged therefrom to prevent the occurrence of leakage current in bus bar circuit boards or the like mounted in the box.
The construction of a conventional electrical connecting box, such as a junction box or a relay box, is generally as shown in FIG. 1.
In FIG. 1, reference numeral 1 designates a bus bar circuit board on both sides of which bus bar circuits 2 are provided; 3, a top plate on which are mounted connector housings 4, to which, for instance, relays are connected.
In general, a plurality of bus bar circuit boards 1 are provided in a multi-layered arrangement. In each of the bus bar circuit boards, tab terminals extend upwardly and downwardly from the bus bar circuits 2, and some of the tab terminals of the bus bar circuit boards 1 located between the uppermost and lowermost bus bar circuit boards, extend upwardly through the uppermost bus bar circuit board or downwardly through the lowermost bus bar circuit board.
The tab terminals 5 are inserted into the connector housings 4 mounted on the top cover 3 placed over the bus bar circuit boards 1 or into connector housings provided on the bottom plate 6a of the box body 6.
The top plate 3 and the bus bar circuit board 1 are placed in the box body 6. The upper opening of the box body 6 is covered with a waterproof cover 7, and the lower opening of the box body 6 is covered with a connector cover 8, as shown in FIG. 2, which is the bottom wall of the electrical connecting box. The electrical connecting box further includes mounting brackets 9 which ar connected to the body of the vehicle with bolts or the like.
As described above, the upper and lower openings of the box body 6 are covered with the waterproof cover 7 and the connector cover 8, respectively. However, sometimes water may enter the electrical connecting box through gaps between the covers and the box body when installed on a vehicle, especially when installed in the engine compartment, due to splashing of water from the road or due to water condensation arising from large temperature changes. Furthermore, when the vehicle is washed, water may enter the box through the gaps.
Water entering the electrical connecting box, as shown in FIG. 3, can fall on the uppermost bus bar circuit board 1 through a terminal inserting hole 4a formed in the connector housing 4, thus wetting the bus bar circuit 2A on the bus bar circuit board 1. As a result, the bus bar circuit 2A may suffer from current leakage.
The male terminals 5 extending outwardly from the bus bar circuits 2A and 2B of the bus bar circuit boards 1 are engaged with female-female terminals 10. Water droplets G from the bus bar circuit may contact the two female-female connectors 10 or collect between two bus bars having a potential difference, thus causing current leakage.
Therefore, water droplets G entering the electrical connecting box should not be retained on the bus bar circuit; that is, it is essential to quickly remove water droplets G from the electrical connecting box. However, there has been no suitable means for quickly removing such water droplets G from the space over the bus bar circuit covered by the top plate 3.